After experimenting with very limited small batches, decorated Aurora brewery Dry Dock[4] is about to expand its sour beer repertoire – another sign of growth in what remains a niche category of American craft beer.

Sometime this week, Dry Dock anticipates it will fill seven just-arrived chardonnay barrels with beer that will age for about six months and emerge as a sour apricot, owner Kevin DeLange said.

The brewery made limited editions of sour apricot and sour saison for a recent breast cancer-awareness fundraiser and set aside a couple kegs for anniversary parties, DeLange said.

“We want to do a limited quantity first and figure out what’s working well – what kind of bacteria, barrels and beer go well together,” DeLange said.

Dry Dock adds both the wild yeast Brettanomyces and Lactobacillus in the sour brewing process; the brewery has whiskey and spirit barrels on hand for aging in addition to the white wine barrels.

Sours represent a small but growing segment of craft beer, a logical next step for drinkers ready to move on from IPAs and other popular styles to more experimental beers. New Belgium[7] was a pioneer in the field, introducing its Flanders-style red, La Folie, way back in 1999.

Yet DeLange and others say it’s unlikely sour beer will ever be huge considering the time and cost of producing them, among other factors.

“I think it’s been fantastic, both in terms of the public reaction to sour beers and the variety and number of sour beers,” DeLange said. “It’s been exploding in the last few years. It’s a really fun project for brewers to be able to do on the side in relatively small quantities, in these barrels. But each brewery is making a limited amount of them. They are always going to be fairly expensive and in short supply.”

DeLange said Dry Dock probably won’t package the sour apricot, choosing instead to serve it on tap at its tasting room and more widely distribute it in kegs around town.

However, Dry Dock is in the hunt for a new production facility for a 40 barrel brewhouse – with bottling sours as part of the plan. DeLange said Dry Dock will set up a separate bottling line for sour beers, which is critical to keep the bacteria and wild yeast from contaminating other equipment and beer.

So sometime in the near future, Dry Dock will be able to package its fledgling sour beer efforts in 750 ml Champagne bottles – if the calendar cooperates, maybe even some of the beer going into barrels this week.